Recently, while global environment problems are attracting attentions intensively, there is required a reduction in emission of greenhouse gases in every fields in order to prevent global warming. A gasoline-engine automobile considered as the largest emission source of the greenhouse gases comes to be replaced with a hybrid electric automobile and an electric automobile.
A large-scale secondary battery used as a power source of the hybrid automobile and the electric automobile is required for a high power and a large capacity. Therefore, a storage battery module equipped in the large-scale secondary battery is configured by connecting a plurality of battery cells in series and parallel.
A lithium ion battery as the secondary battery is required to be appropriately handled in order to prevent a high-voltage charge and to prevent degradation in performance due to an overdischarge. Therefore, the battery module mounted in the hybrid automobile or the electric automobile is provided with a battery management device which detects voltage, current, and temperature as a battery status. A battery system controller receives a notification on the battery status from the battery management device, and controls the battery according to the battery status.
When being overcharged or excessively increased in temperature, the lithium ion battery is significantly degraded in performance, and there is also increased a risk of fire or explosion. Therefore, when the overcharge and the excessive temperature rise are detected, it is necessary to take a measure such as immediately disconnecting the battery from an external circuit. It is considered that a configuration to immediately notify an abnormal status of the battery to the battery system controller as described above is important.
PTL 1 discloses a technique in which a communication system for a normal communication and a communication system for an abnormality notification are provided between controllers of non-contact power transmission apparatus. In a case where the technique disclosed in PTL 1 is used in a battery control system, it may be considered that a first communication path for the normal communication and a second communication path for the notification of a battery abnormality are provided between the battery management device and the battery system controller. When an abnormality occurs in the battery monitored by the battery management device, the abnormality is notified to the battery system controller using the second communication path.